ECOSYSTEMS

 

ECOSYSTEMS

          The term ecosystem was coined by Tasnley.  The living community of plants and animals is any area together with the non-living components of the environment constitute the ecosystem.

 
ABIOTIC COMPONENTS

It refers to non-living things, such as air, water, light, soil, temperature etc,.

BIOTIC COMPONENTS

It refers to living things such as plants and animals.

The biotic factors of an ecosystem are classified in to three main categories namely:

1. Producers

2. Consumers

3. Decomposers

 

Plants, which produce their own food, are called auto trophsas the manufacture their food by using energy from the sun.

The consumers are the living organisms other than plants, which depend on other organisms for their food.  They are further divided into three types.  They are:

1. Primary Consumers

2. Secondary consumers

3. Tertiary consumers.

 

1. PRIMARY CONSUMERS:

          The herbivorous animals are primary consumers. They eat the producers like plants, algae etc., (eg) rabbit, deer, cow, goat, etc.,

 

2. SECONDARY CONSUMERS:

          They are animals which feed upon the primary consumers eg. Fox, snake, eagle etc.,

 

3.  TERTIARY CONSUMERS:

          Tertiary consumers are carnivores that feed on primary and secondary eg. lion, tiger, etc.,

 

DECOMPOSERS:

          Organisms consisting of bacteria and fungi which breakdown dead organic material into smaller particles and finally into simple substances that are used by plants as nutrition.  In this process, chemical elements present in the dead bodies are released back to the nature.

ENERGY FLOW THROUGH ECOSYSTEM:

          When the green plants prepare food in the presence of sunlight they store energy in the food.  When consumers like deer, cow, rabbit etc., feed on the producers the energy found in plants gets transferred to these animals.  Thus there is an energy flow.  The transfer of energy from producers through a series of organisms takes place in food chain.  Thus the different plant and animal species are linked to one another through food chain.

FOOD CHAIN:

          The sequence of the eaters the being eaten is called food chain.  for eg the producers from the food for the herbivores.  The herbivores form the food for the carnivores.

 

1. FOOD CHAIN IN GRASS LAND ECOSYSTEM:

           In a grass land ecosystem, the food chain starts from grasses and goes through the grass hopper, lizard, snake and the eagle in an orderly sequence.

2.  FOOD CHAIN IN A MARINE ECOSYSTEM:

          An example of food chain in marine ecosystem may be represented as follows:

FOOD WEBS:

          In an ecosystem the various food chains are interconnected with each other to form a network called food web.

For example: in a grass land ecosystem the grass is eaten by grasshopper, rabbit and mouse.  Grasshopper is eaten by garden lizard which is eaten by eagle.  Rabbit is eaten by eagle.

 

ECOLOGICAL PYRAMIDS:

          The number, biomass and energy of organisms gradually decreases from the producer level to the consumer level.  If this represented in the form of a diagram It is called ecological pyramid.  There are three types of ecological pyramid.

1. The pyramid of number

The number of individuals at the trophic level decreases from the producer level to the consumer level.

2. The pyramid of biomass

The pyramid of biomass refers to the total weight of the matter per unit area.

3. The pyramid of energy

It refers to the energy flows in an ecosystem from the producer level to the consumer level.

In the pyramid the producer forms the base and the final consumer occupies the apex.

BIOGEOCHEMICAL CYCLES:

          The cyclic path of the elements from the abiotic system to the biotic system and back is called biogeochemical cycle.  Every ecosystem is controlled by biogeochemical cycles.  In each ecosystem abiotic and biotic features are distinct from each other.

1. CARBON CYCLE:

          The cycling of carbon between biotic and abiotic system is called carbon cycle.

          In the atmosphere carbon occurs as carbondioxide.  In the presence of sunlight plants take up co2 from the atmosphere and able to form carbohydrates that contain carbon.  In this process plants release oxygen in to the atmosphere.

          Both plants and animals release co2 during respiration.  They also return fixed carbon to the soil when they die.  These processes complete the carbon cycle.

2. OXYGEN CYCLE:

           Oxygen is absorbed by plants and animals from the air.  The plants return oxygen to the atmosphere during photosysthesis certain amount to oxygen in atmospheric air is converted in to ozone.  Ozone prevents UV radiation from reaching the earth surface.

3. NITROGEN CYCLE:

          Nitrogen is an important nutrient of plant.  Plants cannot utilize free n2 from air.  Plants obtain n2 from nitrites and nitrates.  These compounds are formed from atmospheric nitrogen by nitrogen fixation.  The conversion of molecular nitrogen into ammonia is known is nitrogen fixation eg., Azotobacter etc., Micro organisms can deaminate aminoacites.  The production of ammonia is referred to as ammonifiation.  Micro organisms convert ammoia to nitrate and the process is called nitrification.  The fixed nitrogen is absorbed by plants through the root system.  The sequence to changes from free atmospheric nitrogen to fixed inorganic nitrogen, to simple organic compounds to complex organic compounds on the tissues of plans and animals and micro organisms and the eventual release of this nitrogen is back to atmospheric nitrogen.

4. WATER CYCLE:

          Water is drawn up from the ground by plants along with the nutrients from the soil.  The water is then returned to the atmosphere as water vapour.  Water vapour from ocean surface and other water bodies enters the atmosphere.  As it is lighter than air, water vapour rises and forms clouds.  The wind blows the clouds to high altitudes where the vapor condenses and changes in to droplets, which fall on the land as rain.

ECOLOGIGAL SUCCESSION:

          Ecological succession is a process through which ecosystem tent to change over a period of time.  Succession can be related to seasonal environmental changes, which create changes in the community of plants and animals living in the ecosystem.  The most frequent example of succession changes occur in a pond ecosystem, where it fluctuates from a dry habitat, after the monsoon, which gradually passes through to aquatic ecosystem and then reverts back to its dry stage in summer when it’s aquatic life remains dormant.

 

MAJOR ECOSYSTEMS:

          The ecological characteristic of the major ecosystems are given below:

1. Forest ecosystem:

          In India, the forests occupy 19% if the total land area.  The major forest biomes found in India are:

          1. Tropical rain forests grow in the high rainfall areas of the     western ghats and the Andaman and nicobar islands.

          The trees have broad leaves.

          The forest is rich in ochids and ferns.

          Tropical rain forest have the richest diversity of plants and animals species.

          2.Tropical deciduous forests are found in regions with a moderate   amount of seasonal rainfall.  The deciduous trees shed their    leaves during the winter and hot summer months.

          3. Coniferous forests grow in the Himalayan mountain region           where the temperature are low.  The forests have tall trees with      needle like leaves.  The snow leopard lives in the Himalayan broad     leaved trees have large of various shapes and are found in middle     to lower latitudes.

Abiotic components include soil, water, air, sunlight, temperature etc.,

Biotic factors include plants and animals

1. Producers: A few herbs and shrubs grow as producers.

2. Consumers: Various types of consumers in forest ecosystem a follows

a) Primary consumers: Herbivores animals such as elephants, deer, moles, squirrels etc.,

b) Secondary consumers: Common animals feeding on herbivores are snakes, lizards, birds are present

c) Tertiary consumers: These are the animals which feed on consumers such as lion, tigers etc.,

d) Decomposers: Bacteria and fungi decay the dead organic matters.

 

GRASSLAND ECOSYSTEM:

          Grass lands form a variety of ecosystems.  It occur on hill  slopes. Grass lands cover areas where rainfall is low and the soil depth and quality is poor.  Grass land ecosystem has a wide variety of species of grasses and herbs.

 

ABIOTIC COMPONENTS:

          Abiotic components include soil , water, light, temperature etc.,

 

BIOTIC COMPONENTS:

1) Producers: Producers are the grasses they synthesis food.

2) Consumers: Consumers in grass land ecosystem are as follows:

          a. Primary consumers:

          Herbivores are mainly grazing animals such as buffaloes, cows, deer, sheep and rabbits.

          b. Secondary consumers:

          Common animals feeding on herbivores are snakes, lizards, birds etc.,

          c. Tertiary consumers:

          Hawks feeding on secondary consumers

          d. Decomposers:

          Bacteria and fungi decay the dead organic matter of plants and animals.

 

DESERT ECOSYSTEM:

          Desert are characterized by scanty flora and fauna.  It occupied one fifth of the earth surface.  In the desert area temperature is very high rainfall is less than 10cm.  The most typical desert landscape seen in rajasthan is in the Thar Desert.  this is sand dunes in most area of the thar the rainfall is scanty.

Abiotic components:

          Abiotic components include water, air, light, temperature etc.,

Biotic components:

          Biotic components include plants and animals.

          The animals of these dry areas have highly specialized adaptations like water conserving mechanism.

 

AQUATIC ECOSYSTEM

Aquatic ecosystems:

          In aquatic ecosystems, plants and animals live in water.  The aquatic ecosystems comprise of the marine environments of the sea and the freshwater system in lakes, rivers, ponds etc.,  The aquatic ecosystems are classified into freshwater, marine and estuary which are based on the salinity livel.

          The fresh water ecosystems that have running water are streams and rivers.  Ponds, tanks and lakes are freshwater ecosystems where water does not flow.  Marine ecosystems are highly saline while brackish areas have less saline water such as in river deltas.  Brackish water ecosystems in river deltas are covered by mangrove forests.

Pond ecosystems:

          The pond is the simplest aquatic ecosystem.  It contains shallow standing water.  Ponds has water only in the monsoon season.  Most ponds become dry after the rains are over.  Abiotic factors are water,  CO2, o2, light, temperature, pressure, ph etc.,  Biotic factors are plants and animals producers synthesize food from abiotic factors

          Consumers eat other organisms primary consumers eaten by the secondary consumers e.g, small fishes, frogs.

          Secondary consumers are eaten by tertiary consumers large fishes, snakes etc.,

          Decomposers are organisms that break up the dead bodies of other organisms eg. Bacteria.

 

River Ecosystem

·       Rivers are flowing water ecosystems.

·       It has water current.  All the living forms are specially adapted to different rates of flow.

·       River ecosystem is made up of abiotic and biotic components

·       Abiotic components includes river, soil, water, light, temperature etc.,

·       Biotic components are of 3 types

·       Producers are the plants

·       Consumers are the animals

·       Herbivores eat the plants

·       Carnivores eat the animals

·       Decomposers break the dead bodies

·       Energy flows from the producers to consumers

The river have a sandy, rocky or muddy bead, each type having its own species of plants and animals.

 

Lake ecosystem:

lake has water throughout the year

·       A large freshwater body-no connection with the sea

·       Lake has water throughout the year

·       Lake is of 3 types

·       Oligotrophic lakes are defined as deep in depth – poor in fauna and flora.

·       Eutrophic lakes are defined as shallow- rich in fauna and flora

·       Dystrophic lakes are defined as shallow or deep – poorin fauna and flora

 

MARINE ECOSYSTEM:

·       It comprises the sea and oceans.

·       It is the largest ecosystem in the world.

·       The Indian ocean, the Arabian sea and the bay of Bengal constitute the marine ecosystem.

·       Consists of abiotic and biotic factor.

·       Marine plants constitute the producers

·       Marine animals form the consumers like herbivores and carnivores, eg., fish, turtles etc.,

·       Herbivores feed the producers

·       Carnivores feeding on other animals

·       Decomposers break the dead bodies of plants and animals

·       The minerals and nutrients enter the body of the producers

·       From the producers they entry  the animals